Department of Applied Physics, University of Eastern Finland, 70211 Kuopio, Finland.
Biomech Model Mechanobiol. 2012 May;11(5):665-75. doi: 10.1007/s10237-011-0341-z. Epub 2011 Aug 30.
The objective of this study was to evaluate the effect of sample preparation on the biomechanical behaviour of chondrocytes. We compared the volumetric and dimensional changes of chondrocytes in the superficial zone (SZ) of intact articular cartilage and cartilage explant before and after a hypotonic challenge. Calcein-AM labelled SZ chondrocytes were imaged with confocal laser scanning microscopy through intact cartilage surfaces and through cut surfaces of cartilage explants. In order to clarify the effect of tissue composition on cell volume changes, Fourier Transform Infrared microspectroscopy was used for estimating the proteoglycan and collagen contents of the samples. In the isotonic medium (300 mOsm), there was a significant difference (p < 0.05) in the SZ cell volumes and aspect ratios between intact cartilage samples and cartilage explants. Changes in cell volumes at both short-term (2 min) and long-term (2 h) time points after the hypotonic challenge (180 mOsm) were significantly different (p < 0.05) between the groups. Further, proteoglycan content was found to correlate significantly (r(2) = 0.63, p < 0.05) with the cell volume changes in cartilage samples with intact surfaces. Collagen content did not correlate with cell volume changes. The results suggest that the biomechanical behaviour of chondrocytes following osmotic challenge is different in intact cartilage and in cartilage explant. This indicates that the mechanobiological responses of cartilage and cell signalling may be significantly dependent on the integrity of the mechanical environment of chondrocytes.
本研究旨在评估样本制备对软骨细胞生物力学行为的影响。我们比较了完整关节软骨表面和软骨标本切割面中浅层区（SZ）软骨细胞在低渗刺激前后的体积和形态变化。通过共聚焦激光扫描显微镜对 calcein-AM 标记的 SZ 软骨细胞进行成像，分别穿过完整软骨表面和软骨标本的切割面。为了阐明组织成分对细胞体积变化的影响，我们使用傅里叶变换红外显微镜估计了样本的蛋白聚糖和胶原含量。在等渗介质（300 mOsm）中，完整软骨样本和软骨标本之间的 SZ 细胞体积和纵横比存在显著差异（p < 0.05）。在低渗刺激后（180 mOsm）的短期（2 分钟）和长期（2 小时）时间点，细胞体积的变化在两组之间也存在显著差异（p < 0.05）。此外，我们发现，在具有完整表面的软骨样本中，蛋白聚糖含量与细胞体积变化显著相关（r² = 0.63，p < 0.05）。胶原含量与细胞体积变化无相关性。结果表明，在完整软骨和软骨标本中，软骨细胞在渗透压刺激后的生物力学行为不同。这表明，软骨的机械生物学反应和细胞信号转导可能高度依赖于软骨细胞机械环境的完整性。
